Can I control an object using a driver with multiple inputs?
I got it working like I wanted to:



Upper eyelid

Just add both values (slider and ctrl_up) as variables and use Type: Minimum Value, since they are going from positive to negative and we want the smallest one.



Lower eyelid

Just add both values (slider and ctrl_down) but use Type: Scripted expression, and invert var2, so when it moves up, it still gives a negative number.



Here's the final blend:


Hope this helps someone with understanding drivers!